1. Field of the Invention
The present invention relates to an improvement in mechanical vibration analyzers and more particularly to a mechanical vibration analyzer which includes a "quik-look" visible display octave analyzer.
2. Description of the Prior Art
Mechanical vibration analyzers are well-known. See U.S. Pat. Nos. 2,711,647, 3,205,713 and 3,938,394. Octave band analyzers and fractional octave band analyzers are well-known in the electronics industry as devices for instantaneously observing the relative wave energy content of a multi-frequency wave phenomenon, e.g., an acoustical signal.
In the past, mechanical vibration analyzer equipment has included a mechanical vibration detector which converts instantaneous mechanical vibrations into corresponding cyclic electrical signals having wave components at multiple electrical frequencies. The vibration analyzers also include narrow band electrical filters for selecting various electrical frequency components within a narrow range of frequencies. The instantaneous amplitude of the electrical wave signals within the narrow filter band is observed. For example, the amplitude of the narrow band electrical signals is displayed in a voltmeter scale which may be suitably calibrated to indicate the corresponding mechanical vibration values, such as displacement, velocity, acceleration.
By employing variable frequency band filters in prior art mechanical vibration analyzers, it is possible for the operator to scan through multiple frequency ranges and observe the instantaneous mechanical vibration amplitude in each observed frequency range. This is time-consuming, particularly at lower frequencies where the electrical filter components require substantial time lapse to achieve equilibrium conditions. At any one instant, the prior art devices display only the amplitude existing for the particular frequency band selected by the operator. If the operator is seeking peak amplitude phenomena, it may be necessary for the operator to conduct a frequency scan over the entire spectrum of frequencies which the mechanical vibration analyzer is capable of observing.
Accordingly it would be desirable to have a mechanical vibration analyzer which can supply a qualitative indication to the operator of the instantaneous mechanical vibration amplitudes in various frequency bands over the range of vibration frequencies which the analyzer is capable of observing. The operator thereby can quickly and effectively target the range of vibration frequencies which should be subjected to more intensive observation in the analyzer equipment.
Recent developments in vibration analyzers having digital readout presentations have created a difficulty in fine tuning the analyzer filters. Prior art analyzers have meter-deflection readout presentations providing a useful fine tuning indicator for the analyzer filters. See U.S. Pat. No. 3,228,235. The operator could easily detect peak deflections and thereby fine tune the filter.
A buckets and arrows technique has been described in copending U.S. patent application Ser. No. 76,030, filed Sept. 17, 1979, which requires supplementary apparatus for the fine tuning function in vibration analyzers having digital readout presentations.
A quick visual fine tuning device for an analyzer filter would be desirable in a vibration analyzer having a digital readout display.